1. Field of the Invention
The present invention relates to the storage and retrieval of e-mail messages. More particularly, it relates to synchronizing e-mail messages for the same user amongst multiple mailboxes, on heterogeneous servers.
2. Description of the Related Art
An e-mail user may have more than one e-mail account on different mail servers. Mail for the user may be forwarded to one of the servers, or mail may be consolidated at one server.
This creates duplicate e-mail messages on the different servers. Each of the duplicate messages then must be separately read and deleted, unfortunately requiring additional time and attention from the user.
This problem is particularly acute for mail servers where there is no conventional technology enabling synchronization between two or more such mail servers. An example of this is POP3 mail servers. Most commercial external e-mail servers offer only the POP3 protocol for e-mail retrieval, thus making the problem both more universal and more severe.
The IMAP4 protocol was built to solve the mailbox synchronization problem, however, it is not available on most interne email servers.
Various formats for e-mail messages have been prescribed. One widely-used standardized format for e-mail message is encouraged by RFC 822, expressly incorporated herein by reference. These standards use, among other things, a message identifier which is intended to be unique to an e-mail. These standards do not, however, provide a way to synchronize or consolidate e-mail.